Locally I'm getting a high pitched whining hetrodyne type noise every 4khz it never goes away in between each 4khz turn of the vfo only rises and falls and rises again!

Up to now it's wiping out top band and 20 metres ...Iv looked for it with loops, ferrite rod antennas ..20 metre whip antenna on the car and on foot..cant trace it..driving me crackers !

All this with the S9 noise floor ....thats to be tackled.

I have read about psu to modems etc..Had neighbours switching mains off etc..some very cagey and hard to approach .

Had one neighbour swapping a psu out for one I supplied with a proper transformer in it . Iv tried .

My own house is in order. Help.

Once had Ofcom here to sort next doors plasma out ..made many excuses and they were nothing short of US ..i was left with the problem for 7 years..wiping everything out 20 db over. That neighbour knew the effect it had on my equipment and my life long l9ve of all things radio and when the offending plasma went kaput he went out and bought another rotten plasma.. sneaky . I caught him out on it after a further two years of suffering it's noise.

Went off on one there ! Sorry . Best 73 all. Any help appriecieted. 73.

Every 4kHz sounds remarkably like someone's broadband modem retraining itself, that happens when it loses the VDSL signal. It's very difficult to find the culprit as you can imagine it radiates across all the telephone lines. Does it appear on any other band? Have you checked?

Have a look at this document, the bottom of page 3.
https://www.dropbox.com/s/gqodlbte2r2sq ... 3.pdf?dl=0

Hello Paul and thanks, I will check all other bands..I went through it all 3 years ago and gave up in the end , .Im back on the trail . Im sure iv got a log of all this from yonks ago . Will report back . Thank you. Andy.

Morning Paul , The wining is right through top ban , also 80metres up to 3.700 give or take a few kHz, nothing much on 40m, 20 metres right through the band ..terrible. 15 metres 10 metres clear. I was checking on the Drake R4B so missed out the warm bands ..will do that Monday. I imagine it will all stop around 17.660 .

Will check the guard bands next....

All interesting stuff although I'v done most of it in the past and got nowhere.

It'll be an Ofcom job.

Like you say Paul hard to track down. 73. Andy.

If the noise stops at 17.660MHz then it's almost certainly VDSL. Checking the guard bands will be another good indicator, the noise should drop to zero.

You can try OFCOM, but they tend to like to bury their head in the sand over VDSL complaints, but give them a try you never know.

I'm surprised that the noise is still there after all this time, that means whoever's modem is playing up they are getting absolute crap download speeds, from my experience of the next door neighbour they were getting in the region on 1-2mb/s download speed instead of the 80mb/s they were paying for. He had placed the modem in another room with a long piece of wire to the faceplate which unbalanced the whole of his system and I was getting the same as you with the comb of carriers every 4kHz, I got him to place the modem next to the incoming faceplate and it all started working as it should. They were over the moon that I told them what the problem was and got their internet back again.

It will be almost impossible to find out where the problem modem is, it might be worth leafleting all your direct neighbours and asking them to test their download and upload speeds and to let you know if they are not getting the speeds they are paying for. How good a diplomat are you?

https://speedof.me/

Hi Paul , thanks for you're advice and take on it all. I have just returned from a trip from the far end of Scotland and will message you later in the day. Knackered ! 73. Andy.